This question ( Saturday Sabbath ) was raised in the time of the Apostles & was presented as a matter of Salvation…
…To which Sacred Scripture speaks.
Acts 15:
But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, AND to command them to keep the law of Moses
In Judaism one could NOT observe the Sabbath w/out being circumcised…
…It was the “gateway” to being a part of Israel.
…In fact the Jewish teaching was that a Gentile who attempted to keep Sabbath.
…Deserved to die.
In the Book of Acts, chapter 15 we can read how some Jewish converts to Christianity…
…Attempted to force the law of Moses on Gentile converts to Christianity.
…What follows is the Apostolic teaching on why that understanding is false.
What remains in force is the Moral or Natural Law of God…
…Which is perpetual and in force at all times.
…Such as murder, stealing, sleeping with another mans wife, etc,etc,etc.
…Actions we are instructed by “Nature” to abstain from.
While we can see every culture in history has had rules dealing with stealing, murder, etc…
…Man is not commanded by Nature to observe a Saturday Sabbath.
…Therefore the Sabbath, as to time celebrated, is part of the Jewish ceremonial law.
…Which was closed out by Christ.
…And was ONLY intended for the Jews.